Vitamin IV delivers vitamins B, C and D intravenously or intramuscularly to correct a deficiency quickly. B is involved in energy metabolism, C in antioxidation and collagen synthesis, D in bone and immunity. Because it skips oral absorption, blood levels rise quickly, and if you were deficient the effect is clear.

Once a week is recommended. Change is felt between one and four weeks, and when depends on which vitamin was deficient and by how much. Repeating without a deficiency simply means water-soluble vitamins leave in your urine, so testing first is the better route.

The effect is clear when a blood test confirms a deficiency first. If you have kidney disease, excretion is impaired and substances can accumulate, so you must disclose it. Repeated high doses need a consultation, and vitamin D in particular is fat-soluble and accumulates.